How to Bridge ETH to Arbitrum: Step-by-Step Guide

Transferring ETH to Arbitrum involves sending it through the official Arbitrum Bridge and locking it on Ethereum, thus minting the corresponding amount on Arbitrum One. In general, it takes about 10 to 15 minutes to receive the deposit on the platform. Thus, it is the easiest and safest way to get ETH on Arbitrum.

On the other hand, the process of returning ETH to the Ethereum network is quite different and takes significantly more time. This peculiarity should be considered ahead of time to prevent potential confusion for someone using the bridge for the first time.

What Exactly Is Bridging ETH to Arbitrum?

Arbitrum One is a Layer 2 solution created by Offchain Labs on top of Ethereum based on the optimistic rollup concept. Such a concept allows bundling transactions off-chain and settling them periodically on Ethereum. This is what allows Arbitrum to offer lower costs and faster transactions compared to Ethereum's base layer.

The bridge is a tool that enables this connection. In the case of a deposit of ETH, it does not literally transfer the assets to Arbitrum. Rather, the contract on Ethereum locks the original ETH in escrow and creates an equivalent amount on Arbitrum One, which stays tied to that locked ETH for the entire time it sits on Layer 2.

Bridging ETH to Arbitrum Using the Official Bridge

The official bridge, supported directly by Offchain Labs, is the most secure way to transfer ETH to Arbitrum since it is independent from third parties and uses only Ethereum and Arbitrum's contracts.

• Open the official Arbitrum Bridge and connect a wallet such as MetaMask. Make sure that your wallet is connected to the Ethereum mainnet.

• Choose ETH as the asset and Arbitrum One as the destination network.

• Indicate the amount of ETH you want to deposit. Confirm there is enough extra ETH left over to cover the Ethereum gas fee.

• Confirm the transaction in your wallet and wait for it to be included in an Ethereum block.

• The deposit will appear on Arbitrum One in about 10 to 15 minutes, although the process may be slower in case of congestion on Ethereum.

Why Deposits Are Instant While Withdrawals Take Time

The speed of deposits on Arbitrum is the consequence of a simple truth: locking assets on Ethereum does not require any kind of proof because all parties already trust the Ethereum network completely. Withdrawals work in the opposite direction, and that is where the optimistic rollup model adds a significant delay.

Since Arbitrum One assumes transactions to be valid unless proved to be otherwise and relies on the fraud-proof system, anyone running a validator node may submit a fraud-proof if they discover an invalid state update. Withdrawals on Arbitrum One are possible only after the challenge period expires, which takes about seven days.

How to Withdraw ETH From Arbitrum Back to Ethereum

The process of withdrawing ETH from Arbitrum to Ethereum via the official bridge is very similar to depositing; however, it includes an extra waiting period.

• Open the official Arbitrum Bridge again and connect a wallet to it. Make sure the wallet is connected to Arbitrum One.

• Choose Ethereum as the destination network and enter the amount of ETH you want to withdraw.

• Confirm the withdrawal transaction and pay the gas fee on Arbitrum.

• Wait for the approximately seven-day challenge period to expire, during which the withdrawal will be visible in the bridge interface but not yet claimable.

• After this period, claim the withdrawn ETH on Ethereum and pay another gas fee.

Using Third-Party Bridges for Faster Transfers

Seven days is quite a long time, and that is why there are several third-party bridges designed to make transfers from Arbitrum to Ethereum faster. Services like Across, Hop Protocol, and Stargate rely on pools of pre-funded liquidity and send the equivalent amount of ETH to Ethereum instantly and reclaim the withdrawn amount afterward through the official channel.

However, the difference in the security model is important here. Unlike the official bridge, it does not depend only on Ethereum and Arbitrum's own contracts, but also on the liquidity provider's solvency and the security of the third-party bridge's own contracts. For amounts where speed matters more than minimizing every possible point of trust, this trade-off is often reasonable, but it is a real trade-off rather than a free upgrade.

Bridging ETH Directly From a Centralized Exchange

It is also possible to make the first deposit of ETH to Arbitrum by withdrawing it directly from a centralized exchange to Arbitrum One. For that, you simply need to select Arbitrum as the network when withdrawing ETH instead of Ethereum.

This option can be more convenient for beginners since it does not require holding the ETH in a self-custody wallet on Ethereum first. However, it is essential to check whether the exchange supports the withdrawal of that asset to Arbitrum One, since using the wrong network when withdrawing ETH from a centralized exchange can lead to losses.

Fees for Bridging to Arbitrum

The official bridge does not charge a protocol fee for either deposit or withdrawal. For depositing, you pay only the Ethereum gas fee for submitting the transaction. It varies depending on Ethereum's load level at the time of the transaction.

For withdrawing, you pay two gas fees: one on Arbitrum for initiating the transaction and another one on Ethereum for claiming the ETH after the challenge period. Third-party bridges charge additional fees, usually calculated as a percentage of the transferred amount, for avoiding the waiting time.

Arbitrum One Versus Arbitrum Nova

Another Layer 2 solution developed by Offchain Labs, Arbitrum Nova, has a slightly different structure: while Arbitrum One posts its transaction data directly to Ethereum, Arbitrum Nova has a data availability committee, a set of entities responsible for storing and confirming this data.

The bridge discussed in this guide relates to Arbitrum One and can be used only for transferring funds to this network. Arbitrum Nova has a separate bridge with a different interface. Arbitrum One is the default Arbitrum version mentioned by most wallets and decentralized applications.

Bridge Security and the BOLD Upgrade

At first, Arbitrum had the fraud-proof system that relied on a set of validators permitted to submit a fraud proof. However, the BOLD protocol upgrade introduced permissionless validation: anyone who stakes the required bond can become a validator and submit a fraud-proof during the dispute period.

This matters for bridge security because it removes the need to trust a fixed, pre-approved set of validators to catch fraud. The challenge period under BOLD remains the same as before and is about seven days, but the pool of participants who can enforce it during that window is now open rather than limited to a small group chosen in advance.

Checking Your Bridge Transaction Status

Both deposits and withdrawals may be checked using a block explorer that indicates the confirmation of a transaction or how many days of the challenge period have elapsed in case of a withdrawal. Transactions on Ethereum are checked on Etherscan, while Arbiscan serves the same purpose for Arbitrum One.

The transaction history tab of the official bridge interface also contains information about recently submitted deposits and withdrawals and is the quickest way to find the transaction status.

Why Bridge ETH to Arbitrum

The primary reason people bridge ETH to Arbitrum is to interact with the network's decentralized applications at a lower cost than on Ethereum mainnet. Arbitrum hosts a significant part of the Layer 2 activity of decentralized exchange and lending platforms and also has derivatives platforms that require cheap and fast transactions.

Holding ETH on Arbitrum also allows it to be used as gas for every transaction on the network, even though ETH remains the native gas token on Arbitrum One despite the network being a separate execution environment from Ethereum itself. That is why a person who wants to store any other asset on Arbitrum needs to bridge ETH to the network as well.

ARB Tokens and Arbitrum Governance

ARB is a governance token of Arbitrum, used to vote on protocol-related proposals through the Arbitrum DAO. Holding ARB is separate from holding ETH on the network, and bridging ETH to Arbitrum does not require holding or acquiring ARB at all.

Besides Offchain Labs, the Arbitrum Foundation supports the ecosystem of the project, and major protocol changes are usually discussed within the community of ARB holders in some way before being implemented. This governance layer is not a part of the bridging procedure.

Mistakes to Avoid When Bridging ETH to Arbitrum

There are several mistakes that account for most of the problems related to bridging ETH to Arbitrum.

• Sending funds without having enough ETH in the wallet to cover the gas fee of the deposit transaction.

• Thinking that the withdrawal process will be quick and being confused by the roughly seven-day challenge period of the official bridge.

• Using a bookmarked or search-result link instead of typing the official bridge address directly, which increases exposure to phishing sites designed to look identical to the real interface.

• Failing to remember that the withdrawal process includes the additional step of claiming the funds and paying the Ethereum gas fee after the challenge period ends.